This study tests the hypothesis that 6-year longitudinal stability of behavioral and emotional problems would be greater for children ages 6 to 7 than for those ages 4 to 5 at Time 1. Six-year outcome data for a nationally representative sample of 4- to 7-year-olds (N = 733) were used to examine longitudinal stability of internalizing, externalizing, social, and attention problems. Six-year correlations were high for both age groups, with only 1 of 12 comparisons showing a significant age difference. About 80% of the children maintained their status as deviant versus nondeviant from Time 1 to Time 3 for all problems assessed. The best predictors of Time 3 problem scores were Time 1 and Time 2 scores on the same scale, and age group had no significant effect on regression results. These data suggest that longitudinal stability of behavioral and emotional problems is as strong for children ages 4 to 5 as for children ages 6 to 7 at Time 1. (Contains 7 tables.)